For your question, Premium Security is also Maximum Security. The only difference is the number of devices. However, Premium Security is not being sold anymore to avoid confusions on the naming convention. Thus, Maximum Security has options now for 5 or 10 devices.

The main difference of the Premium and Maximum is the licenses it have. For the Premium Security it has 5 or 10 devices while the Maximum Security has only 3 devices before. But now, there is changes on it. Today, the Maximum Security caters 5 and 10 devices and the Premium Security will not be on the list for the new purchases online on your region while the renewal of Premium security will still be there.